One generally employed method for providing refrigeration to a refrigeration load is to vaporize liquid working fluid thereby transferring refrigeration from the working fluid to the refrigeration load. A problem which may arise in the operation of such systems is two phase instability which is oscillatory in nature wherein the oscillations can have a large enough amplitude that the liquid working fluid is prevented from reaching the area of heat exchange with the refrigeration load. This situation is sometimes referred to as vapor lock. Systems such as thermo-siphon systems, especially at low absolute pressure, may be particularly susceptible to such two phase instabilities.
One application wherein two phase instabilities are particularly troubling is in the provision of refrigeration to superconducting equipment which operates at very low temperatures, typically below 80K. Refrigeration must be provided to the superconducting equipment on a continuing basis in order to maintain the requisite very cold conditions for sustaining the superconductivity. Any loss of refrigeration due to two phase instability would quickly result in loss of superconductivity with potentially devastating consequences.
Accordingly, it is an object of this invention to provide a method for providing refrigeration to a refrigeration load, particularly low temperature refrigeration such as is required for sustaining superconducting conditions, wherein two phase instabilities are reduced or even eliminated.